Rectilinear potentiometer

ABSTRACT

An inexpensive, variable resistance device such as a potentiometer is characterized by a minimum number of parts that include a housing and a cover that is secured thereto without the use of fasteners. The resistance element, the collector and terminal means may be integral with the cover. The wiper element is positioned on a brush block that is suitably mounted on a shaft that is located within the housing. A portion of the brush block extends through the housing for coupling to actuation means.

United States Patent Inventors Arnold S. Louis llutlngs-on-Hudson, N.Y.;

Hans H. Worlnser, New Mlllord, NJ. 875.31 1

Nov. [0, 1969 Dec. 21, i971 Marklte Corporation New York, N.Y.

Appl. No. Filed Patented Assignee RECTILINEAR POTENTIOMETER 4 Claims, 8DrawlngFigs u.s. c1 .Q 338/183, 338/184 Int. Cl. t .t ll0le 9/02 Fieldof Search 338/183,

176,177,178,179,l80,l81,182,197,l99,l84

[56] Relerenees Clted UNITED STATES PATENTS l,82l,927 9/l93l Caruso338/178 2,706,230 ,4/l955 Bourns et al 338/I 83 X 2,873,337 2/1959Bourns et al 338/l80 3,445,802 5/1969 Spaude 338/ l 80 X PrimaryExaminer-Thomas .I. Kozma Assistant Examiner-D. A. Tone Attorney-LeonardR. King ABSTRACT: An inexpensive, variable resistance device such as apotentiometer is characterized by aminimum number of parts that includea housing and a cover that is' secured thereto without the use offasteners. The resistance element, the collector and terminal meansmaybe integral with the cover. The wiper element .is positioned on abrush block that is suitably mounted on a shaft that is located withinthe housing. A portion of the brush block extends through the housingfor coupling to actuation means.

PATENTEDUECZI m 3.629.779

I N VE N TOR ARNOLD .5. L 01/16 B HANS H. WORMJER ATTORNEY RECTILINEARPOTENTIOMETER The aforementioned abstract is neither intended to definethe invention of the application which, of course, is measured by theclaims, nor is it intended to be limiting as to the scope of theinventicin in any way.

This invention generally relates to variable resistance devices and moreparticularly to an improved housing and cover construction for apotentiometer that is inexpensive and simple to manufacture.

There is presently a need for low-cost variable resistance devices suchas potentiometers. The device must be compact and must be susceptible toutilization of the simplest form of manufacturing techniques in order tominimize cost.

In its broadest aspect the present invention provides a plastic housingwhich includes means for supporting a guide shaft. A slideable brushblock is loosely mounted on the shaft and extends through the housing sothat it may be coupled to actuation means. Conductive means andterminals well known in the art are formed on the cover member which, inthe assembled condition, is placed over the open portion of the housingand sealed thereto by heat, solvent or adhesive sealing, or by upsettingat least a portion of the housing edge.

Accordingly, it is an object of this invention to provide an improvedlow-cost variable resistance device.

It is a particular object of this invention to provide a lowcost, sideactuated rectilinear potentiometer.

It is another important object of this invention to provide a device asdescribed above that is readily assembled.

It is a specific object of this invention to provide a low-cost sideactuated rectilinear potentiometer as described above, in which coverfasteners are not required.

These and other features, objects and advantages of the invention will,in part, be pointedout with particularity and'will, in part, becomeobvious from the following more detailed description of the invention,taken in conjunction with the accompanying drawing, which forms anintegral part thereof. In the various figures of the drawing likereference characters designate like parts.

FIG. I is a perspective view illustrating one embodiment of the presentinvention;

FIG. 2 is a transverse, cross-sectional view, in elevation, illustratingthe housing comprising the present invention;

FIG. 3 is an enlargedplan view of the structure shown in FIG. 2;

FIG. 4 is a sectional elevational view taken along line 44 of FIG. 3;

FIG. 5 is a bottom view of the cover element comprising the presentinvention;

FIG. 6 is an end elevational view partially broken away and partially insection of the present invention; the view being taken along line 6-6 ofFIG. 4;

'FIG. 7 is an exploded, perspective view illustrating a brush block andwiper assembly; and

FIG. 8 is a sectional elevational view similar to FIG. 4 with partsomitted for clarity, but illustrating an alternative embodiment.

Referring now to the drawing, there is shown in FIG. I a low-costrectilinear potentiometer 10 comprising the present invention.

With particular reference to FIG. 2 the housing 12 of the potentiometerI0 will be discussed first prior to describing the novel features andassembly procedures of this invention. The housing 12, which ispreferably a molded heat deformable plastic member, is comprised ofsidewalls 14 and 16, a base wall 18 and end walls 20 and 22. The top ofthe housing 12 is open to define a cavity 24 therein and a ledge 25 isprovided proximate the upper edge of the sidewalls I4 and 16. Forpurposes to be described in detail hereinafter the base wall 18 includesa longitudinal slot 26 having walls that converge in a downwarddirection. The convergence of the slot in the downward direction is notessential. It may converge in the opposite direction or be straightwithout affecting the essence of the design. The downward convergenceshown is preferred as it permits broad tolerance in positioning of theshaft within the case and provides a single line of guidance for thebrush block with maximum spacing from the shaft for stabilizing thebrush block. The end walls 20 and 22 each include a slot that is Tshaped in plan view, each of the T-shaped slots comprising a firstrecess 28 and a second recess 30. As shown in FIG. 2, the recesses 28'and 30 do not extend through the end walls. Recess 28 is inward ofrecess 30 and has an arcuate bottom portion 28a. By way of contrast,recess 30 has straight sidewalls and a flat bottom wall. Both of therecesses 28 and both of the recesses 30 are open at their upperextremities.

Turning now to FIGS. 3, 4, 5 and 6, there is shown the potentiometer 10comprising the present invention. A shaft 34 is positioned within thecavity 24 in the housing 12 such that the ends of the shaft 34 rest onthe arcuate bottom surface 28a of the U-shaped recess 28. A moldedplastic, heat deformable brush block 36 is loosely'and slideably mountedon the shaft by means of lugs 38a and 38b. The bottom end extension 40of the brush block 36 extends through theslot 26 formed in the base wall18 and is provided with a notch 42 to permit coupling to an externalactuating device (not shown). The tapered wall of the slot 26 minimizesfrictional contact with the extension 40. Lug 38b is provided with aboss 44 which is arranged to receive a tail portion 46a of a metallicwiper member, 46. An opening 48 in the tail portion 46a is positionedover the boss 44 which is then heated by any suitable tool so as to bedeformed and to thereby capture the wiper element 46.

With the shaft 34 in place, spacers 50 are inserted into each of therecesses 30 as to bear against the top ends of the shaft 34. A cover 52is then inserted into the housing resting on the top surface of thespacers 50 and the ledges 25. It will be appreciated that the sidewallsl4 and I6 and the end walls 20 and 22 of the housing 12 extend above thetop surface of the cover 52. The end walls may be rolled over such asshown by reference character 53 by any heated tool so as to deform theupper edges of the housing 12 and thereby define a lip portion forcapturing thecover member 52. The spacers 50 in combination with wallportions of the recesses 28 and 30 minimize movement of the shaft 34.

In order to complete the potentiometer assembly suitable terminals 54,S6 and 58 are provided extending through the cover member 52 by suitablemeans such as eyelets 54a, 56a, and 58a. On the inside surface of thecover 52 there is formed, in a conventional manner, a conductiveresistance element 60 and a conductive takeoff or collector member 62.The resistance element 60 and the takeoff member 62 are contacted by thebrush 46 which is positioned above the upper surface of the brush block36 and in opposition to the underside of the cover member 52. Theformation of the resistance element 60 and the takeoff member 62 areconventional and do not form a part of the invention other than thattheir combination with the improved housing and assembly thereofprovides an improved apparatus. The housing I2 is also provided withapertures 32a and 32b to permit mounting thereof. The end of theresistance element is connected through an eyelet 59a or other suitablemeans to the top surface of cover 52 wherein printed circuit means 61connects eyelet 59a to terminal 54. This arrangement brings allterminals within the same area facilitating installation in autilization apparatus. Thus the resistor element 60 appears acrossterminals 54 and 58 and the wiper terminal 56 has a direct electricalpath to the wiper member 46.

In FIG. 8 there is shown an alternative embodiment of the presentinvention. In this construction the spacer members 50 described aboveare eliminated. The end wall 22' of the housingl 2 is provided with ablind hole 70 and the opposite wall 20 is provided with an aperture 72that is coaxial with the blind hole 70. A shaft 74 is inserted throughend wall 20' until it seats itself in the blind hole 70. The oppositeend of the shaft 74 which could be splined is retained in aperture 72.The cover member 52' rests on a shoulder 76 formed on the interior ofthe housing I2 proximate the upper edges thereof. The

remainder of the construction is the same as described hereinabove withreference to the first embodiment.

From the foregoing it will be appreciated that an extremely low-costpotentiometer assembly has been provided which avoids the need for coverfasteners. The invention described hereinabove may very easily beassembled merely by dropping the components into place and by deformingthe brush block and the housing, by means of heat, so as to provide aunitary assembly. Adhesives may be used as an alternative to theapplication of heat. The need for tapped holes or the like is eliminatedand there is an attendant reduction in the number of parts that must bemaintained in inventory. Assembly procedures are rapid, do not requirehighly skilled labor and yet provide a reliable device.

It is presently contemplated that the body member be formed of a heatdeformable plastic by conventional molding techniques. However,thermosetting resins may be employed. Further, the body may be formed byextruding the central section from either a plastic or a metal, andemploying suitable end caps. The body member may also be fabricated byemploying conventional sheet metal techniques. If metal is employed forthe body member, an insulating coating may be applied if applicationrequirements so dictate.

Having thus disclosed the best embodiment of the present inventionpresently contemplated, it is to be understood that various changes andmodifications may be made by those skilled in the art without departingfrom the spirit of the inventron.

What I claim as new and desire to secure by said Letters Patent is:

1. An improved, rectilinear potentiometer comprising:

a. an elongated housing including a lip portion on the periphery thereofextending entirely inwardly;

b. a shaft disposed in said housing;

c. means in said housing for supporting said shaft by the ends thereof;

d. brush block with wiper means slidably mounted on said shaft, aportion of said brush block extending through said housing and beingadapted for coupling to an actuation device; and

e. a cover member including a resistance element, a collector andterminal means, said cover member being in nesting relationship withsaid housing and secured thereto by said inwardly extending lip portion.

2. The potentiometer in accordance with claim 1 wherein said means forsupporting the ends of said shaft in said housing includes first recessmeans formed in opposite end walls of said housing, said recesses beingopen upwardly.

3. The potentiometer in accordance with claim 2 wherein there is furtherincluded spacer means intermediate the ends of said shaft and theinterior, opposed surface of said cover member.

4. The potentiometer in accordance with claim 3 wherein there is furtherincluded second recess means in the end walls of said housing, saidspacer means being positioned in said second recess means.

* l t t

1. An improved, rectilinear potentiometer comprising: a. an elongatedhousing including a lip portion on the periphery thereof extendingentirely inwardly; b. a shaft disposed in said housing; c. means in saidhousing for supporting said shaft by the ends thereof; d. brush blockwith wiper means slidably mounted on said shaft, a portion of said brushblock extending through said housing and being adapted for coupling toan actuation device; and e. a cover member including a resistanceelement, a collector and terminal means, said cover member being innesting relationship with said housing and secured thereto by saidinwardly extending lip portion.
 2. The potentiometer in accordance withclaim 1 wherein said means for supporting the ends of said shaft in saidhousing includes first recess means formed in opposite end walls of saidhousing, saiD recesses being open upwardly.
 3. The potentiometer inaccordance with claim 2 wherein there is further included spacer meansintermediate the ends of said shaft and the interior, opposed surface ofsaid cover member.
 4. The potentiometer in accordance with claim 3wherein there is further included second recess means in the end wallsof said housing, said spacer means being positioned in said secondrecess means.